Pressure switch with low pressure cut-out



June 30, 1964 l. W. KRIEGER, SR., ETAL PRESSURE SWITCH WITH LOW PRESSURECUT-OUT Filed Aug. 28, 1962 2 Sheets-Sheet l June 30, 1964 1. w.KRIEGER, sR., ETAL 3,139,493

PRESSURE SWITCH WITH LOW PRESSURE CUT-OUT Filed Aug. 28, 1962 2Sheets-Sheet 2 1NV ENTOR5. im@ Wffgef: 5f,

UnitedStates Patent O of Delaware Filed Aug. 28, 1962, Ser. No. 219,938

7 Claims. (Cl. ZOO-67) The invention relates to electric switches, andhas reference more particularly to pressure actuated switches havingvmechanism for eiiecting an opening of the contacts of the switch at alow pressure below the low pressure of the normal operating range.

The pressureswitch of the invention employs the basic switch elements asshown in the Elsner and McGary Patent No. 3,015,006, grantedDecember 26,1961, the said elements including a toggle member having snap action inresponse to certain pressure conditions to effect opening andclosing ofthe contacts of the switch. Heretofore low pressure cut-off required twoseparate switches, one to operate between the normal low and highpressure range, and a second switch connected in series with a manualreset for opening the contacts in the event the pressure should fallbelow that of the normal operating range. This sometimes happens whenthe pressure fluid fails completely for some reason or other.

. The switch of the invention incorporates mechanism in` addition tothat shown in Patent No. 3,015,006 which,

without interferring with the normal operation of the switch, alsoprovides a cut-out at a third` pressure that is below Athe low pressureof the normal operating range. A reset lever is provided for obtainingnormal operation of the switch and which must be held depressed by theoperator until the pressure in the system builds up to exceed that ofthe low pressure switch-closing setting. The switch thereafter willautomatically maintain the pressure requirements of the system.

Another object of thefinvention is to provide a switch havinga lowpressure cut-olf as described and which will have general utility asregards pressure switch application and uses, since all of the contactsof the switch may be the normally closed or the normally open type withboth ofthe` connecting members being either push rods or pull rods,respectively. A l

With these and various other objects in View the invention may consistof certain novel features of construction and operation, as .will bemore fully described and particularly pointed out in the specification,drawings and claims appended thereto.

In the drawings which illustrate an embodiment of the device and whereinlike reference characters are used to designate like parts- FIGURE l isan elevational view showing a pressure switch having incorporatedtherein the improved features `of the invention;

FIGURE 2 is a vertical sectional View through the switch device ofFIGURE l taken substantially on line l2--2 of said ligure;

FIGURE 3 is a sectional View on line 3-f3 of FIG- URE 1 and showing thepressure lever and adjustable coil spring which form part of the togglemechanism f the switch;

FIGURE 4 is a horizontal sectional View showing the toggle member andtensioning spring and which is taken substantially along line 4-4 ofFIGURE 2;

FIGURE 5A is a sectional view taken horizontally on line 5-5 of FIGURE2;

FIGURE 6 is a top plan view of the contact block of the switch and whichis taken substantially on line 6-6 of FIGURE 2;

FIGURE 7 is a vertical sectional view through the switch of FIGURE 1 andwhich shows the position of the parts when the pressure uid has failedcompletely; and

FIGURE 8 is a vertical sectional View similar to FIG- URE 7, but showingthe position of the parts during normal operation.

The pressure switch of FIGURE 1 has been selected for illustrating theimproved features of the invention and which are best shown in FIGURES 7and '8. The basic structure of the switch proper includes an adaptor orbase portion 10 having a threaded inlet 11 for admitting a fluid underpressure', said base portion 10 being secured by the screws 12 to thesupporting ring 13 of the switch structure. The bottom Wall 14 of thehousing 15, together with the ilexible diaphragm 16 are interposedbetween the parts 10 and 13 so that the switch structure, housing andadaptor are fixedly joined together as a unit. The bottom wall 14 of thehousing has an opening 17 in alignment with the inlet so that thepressure iluid in the inlet is in direct Contact with the undersurfaceof the diaphragm 16 to iex the same in a manner depending on thepressure conditions to which the diaphragm is subjectedl The togglemechanism of the present switch is in turn actuated by the exing of thediaphragm 16 and as the toggle mechanism is caused to oscillate from oneside of a dead center position to the other, the contacts of the switchare respectively actuated.`

The supporting ring structure 13 is accordingly lixedly secured to thehousing and said ring structure has associated therewith the frameassembly 20 and the pivot device comprising the pivots 21 for thepressure lever 22, the said lever comprising the actuating means for thetoggle member as will be presently described. The frame assembly 20 asbest shown in FIGURES 2 and 3 provides the upstanding side walls 23 and24 which are bent outwardly at their upper ends to form the flanges 25and 26. Said flanges in turn support the contact block which isdesignated in its entirety by the numeral 28. The screws 27 extendthrough side extensions formed on the contact block and the said screwsare threaded into the flanges 25 and 26 for releasably securing thecontact block to the frame assembly 20. The side walls 23 and 24 areeach slotted ornotched at 30, FIGURES 7 and 8,

and the pivot ends of the lever 22 are located in the notches forpivotally mounting the lever on the framev assembly 20 with the movableend of the lever 22 being disposed at the right asin FIGURES l, 7 and 8.

The coil spring 32 has encircling relation with the rod 33 which isanchored at its base end in the ring structure 13, and which extendsupwardly from the structure to approximately the top surface of thecontact block 28. The top end of the coil spring 32 is confined by thecap 34 which is threaded on the upper end of the rod 33. The cap can beadjusted on said rod as regards its vertical position so as to vary thecompressive force exerted by the coil spring on the lever 22.

The pivot device providing the pivots 21 includes the base 35 and whichis located in contact with the flexible diaphragm 16 on the top sidethereof and thus the pivot device will move bodily in a verticaldirection as the pressure fluid on the diaphragm causes the same toflex. This bodily movement of the pivots 21 will be transmitted yto thelever 22 and accordingly the said lever will oscillate on its pivot axis30.

One of the improvements of the invention resides in the provision of ailat spring member 36, one end of which is retained between the head ofthe rod 33 and the wall of the ring 13. The other end of the springmember 36, and which is the left end as seen in FIG- URES 7 and 8, isriveted at 37 to the base 35 and also to the diaphragm 16, the rivet 37extending through the several parts. The tension exerted by the atspring memberv 36 is downward so that the base 35 and the pivots 21 arelyieldingly biased `in a downward direction. The toggle member v38 havingthe shape as shown in frame assembly 20. Whereas the pivot ends 30 forthe leverw22 are located at the left edge of each side wall,

the pivot extremities 40l of the toggle member 38 engage in notches onthe right edge of the said side walls.

Also whereas the lever 22 is disposed in surrounding relation with theframe assembly 2.0, the toggle member 38 is located within the frameassembly. This locates the movable end of the toggle member adjacent theheaded screw 41 located in plate 42. Said screw is adjustable -in avertical direction to limit upward movement of the cured to the frameassembly by the screws 27 is preferably formed of a moldable plasticalthough other insulating materials'may be'used. Said block is coredexternallyvto provide the recesses for receiving the metal stripsri onone side of the contact block FIGURE 6 and the metal strips 46 on ltheother side. The terminal screws 47 secure the metal strips 45 to theblock whereas the'screws 48 secure the strips 46 to the block and saidscrews extend into internal recesses and provide the stationary contactsof the switch. The screws 48 provide the contacts for the movablecontact bar 50 and the screws 47 provide the contacts for the movablecontact bar' 51 which is not shown, but which is similar to bar 50. Eachbar is carried by a pull rod 52 in coml bination with a coil spring 53,as Vshown in FIGURES 7 and 8. A pair of the spaced pull rods 52 is shownin FIGURE 3. The coil springs are each confined between Y FIGURE 4 ispivotally mounted at its extremities as Y at 40 on the upstanding lsidewalls 23 and 24 of the ypositions above and below deadr center.

anaaass l ber is caused by the pressure lever in moving to and from lSuch action, will take place during normal pressure vconditions and,accordingly, the contacts open when a pre-set high pressure is reachedand the contacts closes when apre-set low pressure is reached. Shouldthe pressure fluid fail completely then the pivot device, including thebase 35 and Y the pivots 21, is caused to drop since the ilexible di-58, as will be understood byv reference to FIGURES 7 porting structure.The down ymovement.` of the actuataphragm 16 is not under any 'pressureand, in addition, the Hat spring member 36 yieldingly biases the pivotdevice in a down direction.L This action drops the pressure Y lever 22and said lever is thus caused to contact the top projection 62f0rmed onthe arms of the actuating lever and 8. The projections 62 are locatedonthe left side of the pivot axis as shown in said ',gures, and the pres-Y sure of the lever 22 will cause the actuating lever 58 to` move downuntil it rests on the bottom wall of the supand pump it is requiredthatr he cause the contacts of n This is done by actuating the lever theswitch to close. 64 shown in FIGURES 1, 4 and 6. The lever 64 ispivotally secured to the housing 650i the switch and the end 66 of thelever is located under the pressure leverV 22.' The operator can rotatethe. lever 64 to elevate the pressure lever 22, and this action willfree the actuating lever 58 and allow the coil springs 53V to close `thecontacts of the switch. Y

its contact bar and the insulating closure plate 54 throughy which thepull rods extend. The coil springs 53 exert a v compressive forceagainst its contact bar to cause the respective bar to close against the`contacts of the terminal screwsV 47 and 48, respectively. Each pullvrod 52 has a head portion 55 which is located above the contact barsothat when the pull rod is pulled down it also the contacts. t

The pull rods are each formed'with a hook `portion 56 and which extendlthrough openingsy in the toggle t member 38 and engage under the sideextensions 57 of the actuating lever 58 FIGURES 5, 7 and 8. Theactuating lever is part of the present improvement in that said a leverVecects the opening of the switch contacts when the pressure on thediaphragm 16 fails completely.

The actuating lever58 is pivoted` on respective sides rby the U-shapedwire'member 60, the ends of which pass throughthe arms of the lever andalso through the upstanding supports 61.k Since the lactuating lever islocated below the toggle member and also below the pressure lever, thesetwo elementsv have certain `particular Vaction on the actuating lever.'V The hook ends of the pull rods extend Athrough openings in the togglemember and said hook ends are located under the lateral extensions S7ofthey actuating lever. When the toggle member moves down the actuatinglever is also caused tol move down and this'pulls on the rods 52 toeffect an opening of thevswitch contacts. However, when the togglememberfmove's up the actuating lever is not inuenced by it, but by thecoil springs 53 which move the contact bars vand 51-into closingrelation with the stationary contacts provided by the terminal screws 47and 48. This spring action of the coil springs 53 will move the pullrods in an up direction and so the actuatinglever is caused to ,followthe toggle member when it moves upwardly.

Y This up and down, snap movement of the toggle memmoves its contact barin ay downward direction to open 45' Vtoggle member 38 will oscillate asthe pressure varies from a pre-set minimum to a pre-set maximum. Whenthe toggle member moves down it contacts the Vactuating lever 58 and,accordingly, moves the leverdown toin turn open the switch contacts.When the togglemember moves up the pull rods 52'and the actuating leveralso move up due to the action of the coil springs 53. The pressurelever 22 comes intoaction with the projections l62 only when a lowpressure exists which is below the pre-set lowpressure. Then theactuating lever is positively depressed into its low position and theswitch contacts are opened although the toggle member is in an upposition. y y

What is claimed is: Y

l. In a pressure switch,the combination with a supporting basestructure, of a frameassembly secured to said base structure vandAproviding a pairV of spaced upstanding side frames, toggle mechanismpivotally 4supported by the side frames, said mechanism including atogglek member having pivotal movement in a direction parallel to theside frames, a contact block of insulating material xedly supported by.4the side frames and located above" ber, the end of the rod extendingthrough the toggle member having operative association with the`actuating lever, and spring means in associated relation with the rodfor yieldingly forcing the movable contact into closed relation with thexed contacts.

2. In a pressure switch, the combination with a supporting basestructure, of a frame assembly secured to said base structure andproviding'a pair of spaced upstanding side frames, a pressure leverpivotally engaging the sideframes parallel to the side frames, resilientmeans disposed between the pressure lever and the toggle member andconnecting therewith wherebyy the toggle member has movement in oppositedirections between given extreme positions when the pressure lever isoscillated to a predetermined degree, a contact block of insulatingmaterial ixedly supported by the side frames, a plurality of fixedcontacts located within the block and disposed in pairs, a movableContact mounted within the block for coaction with the pairs of Xedcontacts, respectively, a rod operatively connected at one end thereofwith each of the movable contacts, the other end of'each rod extendingthrough the toggle member, an actuating lever pivotally supported by theframe assembly and located below the toggle member, the end of each rodextending through the toggle member having operative association withthe actuating lever, and a coil spring in encircling relation with eachrod for yieldingly forcing its movable contact into closed relation withits pair or" fixed contacts.

3. In a pressure switch as dened by claim 2, wherein each rod is a pullrod and wherein that end of each rod extending through the toggle memberhas operative association with the actuating lever by means of a hookend which is positioned under a side extension provided by the actuatinglever, and additionally including a coil spring in compression relationwith the oscillating end ofk lated in a down direction to apredetermined degree,

whereby the actuating lever is also forced into an extreme down positionand the pull rods are actuated to open the contacts;

5. ln a pressure switch, in combination, a frame assembly providingspaced side walls, a pressure lever having side arms fulcrumed on thefront edges of said side walls and located exteriorly of the walls,relatively movable contacts f carried by the side walls above the lever,a toggle member fulcrumed on the rear edges of the spaced vside wallsand located between the Walls, a spring connecting said pressure leverand the toggle member to pro- Yvide a snap action toggle for saidcontacts, said toggle movable contacts and at its other end to theactuating lever, said pull rod extending through the toggle member so asnot to interfere with the snap action of the toggle member, and saidactuating lever having a projection on its top surface adjacent itspivotal axis for coaction with the pressure lever.

6. ln a pressure switch, in combination, a framek assembly providinglspaced side walls, a pressure lever having side arms fulcrumed on thefront edges of said side walls and located exteriorly of the Walls, apair of iixed contacts carried by an insulating block secured to theside walls above the pressure lever, a movable contact strip mountedwithin the insulating block for coaction with the xed contacts, a togglemember fulcrumed on the rear edges of the spaced side walls and locatedbetween the walls, a spring connecting the toggle member and thepressure lever to provide a snap actionl toggle for said movable contactstrip, the said toggle member having snap action in a direction parallelto the side walls when the pressure lever is oscillated in a directionalso parallel to the side walls, an actuating lever also fulcrumed onthe front edges of the side walls below the pressure lever and extendingbetween the side walls below the toggle member for pivotal movement, apull rod operatively connected at one end to the movable contact stripand at its other end to the actuating lever, whereby down movement ofthe toggle member will eiect similar movement of the actuating lever tocause the pull rod to open the contacts, and spring means associatedwith the pull rod and with the -movable Contact strip to yieldinglyforce the contact strip into contact closing relation withthe iixedcontacts.

7. In a pressure switch as deined by claim 6, wherein the actuatinglever has a top projection relatively adjacentV its pivotal axis forcoaction with the oscillating end of the pressure lever.

References Cited in the file of this patent Y UNITED STATES PATENTS y3,015,006 Elsner et al a Dec. 26, 1961

1. IN A PRESSURE SWITCH, THE COMBINATION WITH A SUPPORTING BASESTRUCTURE, OF A FRAME ASSEMBLY SECURED TO SAID BASE STRUCTURE ANDPROVIDING A PAIR OF SPACED UPSTANDING SIDE FRAMES, TOGGLE MECHANISMPIVOTALLY SUPPORTED BY THE SIDE FRAMES, SAID MECHANISM INCLUDING ATOGGLE MEMBER HAVING PIVOTAL MOVEMENT IN A DIRECTION PARALLEL TO THESIDE FRAMES, A CONTACT BLOCK OF INSULATING MATERIAL FIXEDLY SUPPORTED BYTHE SIDE FRAMES AND LOCATED ABOVE THE TOGGLE MEMBER, A PLURALITY OFFIXED CONTACTS LOCATED WITHIN THE CONTACT BLOCK, AT LEAST ONE MOVABLECONTACT WITHIN THE CONTACT BLOCK, AT LEAST ONE MOVABLE CONTACT WITHINTHE SAID BLOCK FOR COACTING WITH THE FIXED CONTACTS, A ROD OPERATIVELYCONNECTED AT ONE END WITH THE MOVABLE CONTACT, THE OTHER END OF THE RODEXTENDING THROUGH THE TOGGLE MEMBER, AN ACTUATING LEVER PIVOTALLYSUPPORTED BY THE FRAME ASSEMBLY AND LOCATED BELOW THE TOGGLE MEMBER, THEEND OF THE ROD EXTENDING THROUGH THE TOGGLE MEMBER HAVING OPERATIVEASSOCIATION WITH THE ACTUATING LEVER, AND SPRING MEANS IN ASSOCIATEDRELATION WITH THE ROD FOR YIELDINGLY FORCING THE MOVABLE CONTACT INTOCLOSED RELATION WITH THE FIXED CONTACTS.